• Title/Summary/Keyword: blended polyimide

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Generation of High Pretilt Angle for Nematic Liquid Crystal on Blended Polyimide Surfaces Containing Fluorine Moiety (Fluorine 계열의 폴리머를 함유한 복합 폴리이미드 표면에서의 네마틱 액정의 고 프리틸트 발생)

  • Hwang, Jeoung-Yeon;Lee, Kyung-Jun;Seo, Dae-Shik
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2002.07b
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    • pp.949-952
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    • 2002
  • The mechanisms of pretilt angle generation for a nematic liquid crystal (NLC) with negative dielectric anisotropy on the blended polyimide (PI) surface containing trifluoromethyl moiety was studied. High LC pretilt angle on the blended polymer surface with F3 was measured and the pretilt angle increased with rubbing strength. However, the low LC pretilt angle on the blended polymer surface with F1 and F2 was measured. The high LC pretilt angle generated is attributable to trifluoromethyl moiety in backbone structure on the blended PI surface. Therefore, the high pretilt angle of NLC can be achieved by using the blended polymer surface.

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Mechanisms of Pretilt Angle Generation for Nematic Liquid Crystal on Blended Polyimide Surfaces Containing Fluorine Moiety (Fluorine 계열의 폴리머를 함유한 복합 폴리이미드 표면에서의 네마틱 액정의 프리틸트 발생의 메카니즘)

  • 황정연;이상극;서대식
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.15 no.11
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    • pp.981-984
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    • 2002
  • The mechanisms of pretilt angle generation for a nematic liquid crystal (NLC) with negative dielectric anisotropy on the blended polyimide (PI) surface containing trifluoromethyl moiety were studied. High LC pretilt angle on the blended polymer surface with F3 was measured and the pretilt angle increased with rubbing strength. However, the low LC pretilt angle on the blended polymer surface with F1 and F2 was measured. The high LC pretilt angle generated is attributable to trifluoromethyl moiety in backbone structure on the blended PI surface. Therefore, the high pretilt angle of NLC can be achieved by using the blended polymer surface.

EO Characteristics in the Vertical Alignment (VA)-$\pi$ mode LCD Using the Tilt Angle Decrease Effect on the Blended Polymer (혼합된 polymer에서의 틸트 감소 효과를 이용한 VA-$\pi$ mode LCD의 전기광학 특성)

  • Lee, Kyung-Jun;Hwang, Jeoung-Yeon;Seo, Dae-Shik
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2003.05d
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    • pp.53-56
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    • 2003
  • Blending effects for generating a pretilt angle in nematic liquid crystal (NLC) with negative dielectric anisotropy on the blended polyimide (PI) of homeotropic and homogeneous alignment surface were studied. Also, we investigated the EO performances for the advanced VA-$\pi$ cell using this homeotropic blended PI surface. A many decrease of tilt angle on the polymer surface to blend homeotropic PI and homogeneous PI with side chain type was measured, and the tilt angle decreased as blended ratio and rubbing strength increase. The blended effects for generating a pretilt angle were clearly observed, and the many decrease of tilt angle can be achieved by using the blended PI surface. The electro-optical (EO) characteristics using the advanced VA-$\pi$ cell using the homeotropic blended PI surface than that of conventional VA cell can be improved. We suggest that the developed advanced VA-$\pi$ cell on a homeotropic blended PI surface is a promising technique for the achievement of a fast response time, and a high contrast ratio.

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EO Characteristics in the Advanced Vertical Alignment VA-$\pi$ Cell on a Homeotropic Blended Polymer (수직 복합 폴리머 표면을 이용한 Advanced VA-$\pi$ cell의 전기광학 특성)

  • Lee, Kyung-Jun;Hwang, Jeoung-Yeon;Hahn, Eun-Joo;Paek, Seung-Kwon;Seo, Dae-Shik
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2002.11a
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    • pp.530-533
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    • 2002
  • Blending effects for generating a pretilt angle in nematic liquid crystal (NLC) with negative dielectric anisotropy on the blended polyimide (PI) of homeotropic and homogeneous alignment surface were studied. Also, we investigated the EO performances for the advanced VA-$\pi$ cell using this homeotropic blended PI surface. A many decrease of tilt angle on the polymer surface to blend homeotropic PI and homogeneous PI with side chain type was measured, and the tilt angle decreased as blended ratio and rubbing strength increase. The blended effects for generating a pretilt angle were clearly observed, and the many decrease of tilt angle can be achieved by using the blended PI surface. The electro-optical (EO) characteristics using the advanced VA-$\pi$ cell using the homeotropic blended PI surface than that of conventional VA cell can be improved. We suggest that the developed advanced VA-$\pi$ cell on a homeotropic blended PI surface is a promising technique for the achievement of a fast response time, and a high contrast ratio.

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Study of Homeotropic Liquid Crystal Characteristics Using Photo-polymer and Homeotropic Polyimide Blended Alignment Layer via UV Irradiation Method (UV 광배향법을 통한 광폴리머와 수직 폴리이미드 혼합 배향막의 수직 배향 특성 연구)

  • Lee, Jin-Woo
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.25 no.12
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    • pp.996-999
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    • 2012
  • From UV irradiation, we achieved homeotropic liquid crystal alignment on blended photo-polymer layer which is composed of polyvinyl-cinnamate (PVCi) and homeotropic polyimide (PI). From vertical alignment (VA) mode, we measured threshold voltages by various PVCi doping concentration. Also, the rise time and fall time of VA cells were measured to verify the best doping concentration. Transmittance curves showed about 70% value between 380 nm and 780 nm wavelength which mean visible region.

Enhancement of pretilt angle using blending polyimide

  • Lee, Sang-Gu;Shin, Sung-Eui;Choi, Kil-Yeong;Yi, Mi-Hie;Shin, Dong-Myung
    • 한국정보디스플레이학회:학술대회논문집
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    • 2008.10a
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    • pp.317-319
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    • 2008
  • Photo-alignment layer which contains cinnamate is difficult to generate pretilt angle of liquid crystals. In order to enhance pretilt angle, blending poly (amic acid) between containing fluorine poly (amic acid) and 1,2,3,4-cyclobutanetetracaroxylic dianhydride (CBDA) / 3,5-diaminobenzyl alcohol (DBA) were used. For photoreaction, cinnamate was conjugated by interfacial reaction with blending polyimide.

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Enhancement of Molecular Orientation of Liquid Crystal on Photoreactive Polymers by using Non-Photoreactive Naphthalenic Polyimide

  • Hah, Hyun-Dae;Sung, Shi-Joon;Cho, Ki-Yun;Kim, Won-Sun;Jeong, Yong-Cheol;Park, Jung-Ki
    • 한국정보디스플레이학회:학술대회논문집
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    • 2004.08a
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    • pp.1169-1172
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    • 2004
  • Polyimides are blended with photoreactive polymers in order to improve the thermal stability of molecular orientation of photoreactive groups induced by polarized UV irradiation. The polyimide/photopolymer blends can be applied for the photo-induced liquid crystal alignment layers. However, the polyimides are also decomposed by UV irradiation and this may have the negative effect on the orientation of liquid crystals. In order to elucidate the influence of polyimide on the molecular orientation of liquid crystal, non-photoreactive naphthalenic polyimide (1,4,5,8-naphthalene tetracarboxylic dianhydride} was selected for the blend alignment layers. We prepared the blends of photo-reactive coumarin polymers and naphthalenic polyimide, and investigated the orientation of liquid crystals. Thermal stability of the orientation of liquid crystals was enhanced due to the thermally stable polyimide. However, there was no other side-effect of polyimide on the orientation of liquid crystals and this might be attributed to the non-photo-reactivity of naphtahlenic polyimide.

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EO Characteristic in the Advanced Vertical Alignment (VA)- π Cell a Homeotropic Blended Polymer (수직 복합폴리머 표면을 이용한 Advanced VA-π cell의 전기 광학 특성)

  • 황정연;이경준;조용민;서대식
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.16 no.9
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    • pp.826-832
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    • 2003
  • Blending effects for generating a pretilt angle in nematic liquid crystal (NLC) with negative dielectric anisotropy on the blended polyimide (PI) of homeotropic and homogeneous alignment surface were studied. Also, we investigated the EO performances for the advanced VA- $\pi$ cell using this homeotropic blended PI surface. A many decrease of tilt angle on the polymer surface to blend homeotropic PI and homogeneous PI with side chain type was measured, and the tilt angle decreased as blended ratio and rubbing strength increase. However, a small decrease of tilt angle on the polymer surface to blend homeotropic PI and homogeneous PI with main chain type was measured. The blended effects for generating a pretilt angle were clearly observed, and the many decrease of tilt angle can be achieved by using the blended PI surface. The electro-optical (EO) characteristics using the advanced VA- $\pi$ cell using the homeotropic blended PI surface than that of conventional VA cell can be improved. We suggest that the developed advanced VA-$\pi$ cell on a homeotropic blended PI surface is a promising technique for the achievement of a fast response time, and a high contrast ratio.

Pretilt Angle Properties of Mixture Nematic Liquid crystal for Mobile Information Device (휴대용 통신단말에 사용되는 혼합액정계에서의 프리틸트각 특성에 관한 연구)

  • Han, Jeongmin;Seo, Daeshik
    • Journal of Satellite, Information and Communications
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    • v.10 no.1
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    • pp.67-70
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    • 2015
  • We studied the state of the dual liquid crystal (LC) alignment which displays both homeotropic and homogeneous alignment on blended polyimide (PI) layer. The research was conducted using rubbing method at different imidizing temperatures and the blended PI was made using homeotropic PI having an alkyl side chain and homogeneous PI without the side chain. The uniform LC alignments were achieved, and have thermal stability. The results of contact angles were similar to that of pretilt angles.

Electro-optical property of twisted nematic liquid crystal cells with ion-beam irradiated polymer surface (이온빔처리된 고분자막을 이용한 TN 셀의 전기광학특성)

  • Kim, Dae-Hyun;Ok, Chul-Ho;Park, Hong-Gyu;Kim, Byoung-Yong;Hwang, Jeong-Yeon;Seo, Dae-Shik
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2009.06a
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    • pp.338-338
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    • 2009
  • To date, rubbing has been widely used to align LC molecules uniformly. Although rubbing can be simple, it has fundamental problems such as the generation of defects by dust and static electricity, and difficulty in achieving a uniform LC alignment on a large substrate. Therefore, noncontact alignment has been investigated. Ion beam induced alignment method, which provides controllability, nonstop process, and high resolution display. We investigated the high pretilt angle effects on electro-optical properties of ion beam (IB)-irradiated liquid crystal cells. on a blended polymer surface. High pretilt angle of liquid crystals IB-irradiated on a blended polymer surface including such as 5% and 10% of homeotropic polymer contents can' be achieved. The threshold voltages of IB-irradiated twisted nematic (TN) cells on a blended polymer surface decrease with increasing the pretilt angle. Also, the rising time of IB-irradiated TN cells decreases with increasing the pretilt angle. However the decay time of IB-irradiated TN cells increases with increasing the pretilt angle. Consequently, the electro-optical properties of IB-irradiated TN cells depend strongly on the pretilt angle in a blended polymer surface.

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